Los Angeles and Hong Kong are both big, smoggy metropolises on the sea, with active ports, crowded streets and sweltering summers. But for all their similarities, they are opposites in ways they are physically built and run. One is quintessentially American, with car-jammed highways sprawling out over vast expanses of land. The other is a typical Asian metropolis, a hyper-dense city where most people zip around on public transportation and live in packed high-rises.

The photos on the cover of Global Cities says it all. The top photo is of Hong Kong, a city built vertically, with skyscrapers so crowded around the harbour that one wonders if there’s room left at all for the people below. The bottom photo is a landscape shot of Los Angeles at sunset, spread out horizontally like a blanket of city lights.

Urban design has become a hot topic the past few years. For the first time in human history, more people now live in cities than in rural communities. And those city-dwellers are increasingly concerned about their quality of life, as evidenced by the popularity of online lists of “the most liveable cities in the world.” There is growing understanding that cities are not just grids of buildings and highways, but holistic systems which need to be better managed, so that their residents can be afforded clean air, reliable water supply, safe food and sufficient space.

It is in this context that Global Cities was written, to compare two metropolises on opposite sides of the Pacific. The book benefits from the fact that it’s co-written by two authors—one Western, one Eastern—with unique perspectives of their hometowns.

Professor Robert Gottlieb is a veteran American academic based in Los Angeles, who has been involved in American social movements for an astounding fifty years. Simon Ng, a Hong Kong-Chinese researcher, is a Fellow at Civic Exchange, a local think-tank which deals in environmental policy. (For the sake of full disclosure, I am also employed as Civic Exchange, as its Communications Director.)

“Global Cities,” published by MIT Press, is a serious piece of academic writing and the result of years of collaboration between Gottlieb and Ng. (Its endnotes and indexes eat up more than 100 pages of the 400-plus-page length). It is not a personal memoir or colourful novel, but it is not a dryly written study either. The authors do their best to bring the larger issues of urban management to life with practical examples.

They start with a chapter called “A Doll’s Journey” as a way to illustrate the voyage taken by the hundreds of products all of us consume regularly. A doll might be made in a Guangdong factory, possibly one owned by the Hong Kong billionaire sometimes called the “toy king.” It will then be transported to Shenzhen’s busy port and packed in a twenty-foot container along with iPads, T-shirts and other items. It will then cross the ocean on a vessel the size of four football fields before arriving in Los Angeles/Long Beach. A crane will then lift the container onto a truck, then a train, before the doll finds itself in a big-box store, where it will be purchased by a parent or child and driven home. And almost nobody will notice the enormous quantity of emissions and pollution created to get that small object from A to B.

One of the more interesting aspects of Global Cities is its retelling of the two cities’ histories from an environmental perspective. Before reading this book, I would not have imagined that Los Angeles was once “the farming capital” of the United States, or that it used to be a cyclist’s paradise, with its flat terrain and year-round temperate weather. It was in fact rail lines, not highways, that first caused the city’s suburban sprawl.

Eco-activism in Los Angeles started early, around the World War II era. One particularly smoggy day in 1943 was dubbed “Black Monday.” And in the 1950s, a mothers group calling themselves Smog-A-Tears donned gas masks and marched in protest. The night before, the mayor of Los Angeles led a prayer “to deliver us from this scourge” of dirty air. Soon, even LA businessmen were protesting in gas masks; one of their more dramatic banners was “Why Wait Until 1955, We Might Not Even Be Alive.” By the 60s and 70s, environmental concerns had reached the mainstream in American culture.

Meanwhile during this period, Hong Kong was still very much a developing society. After World War II, it was struggling to house waves of refugees from mainland China, while manufacturing was just starting to take off. It was only in the 1990s and 2000s that the Hong Kong public woke up to the issue of pollution, with the creation of groups like the Clean Air Network.

The gas mask—worn ironically as a sign of protest fifty years ago in Los Angeles—is now a common object among commuters in some of China’s more polluted cities. As industrialisation and development moved East over the past decades, so did its environmental problems.

Los Angeles and Hong Kong, like countless other cities, do not produce nearly as many natural resources as their citizens need. Both were relatively self-sufficient in the past, but now rely heavily on imports for basics like freshwater and food. What happens when the world becomes more dominated by cities, and less by the countryside that supplies those cities?

The latter part of the book is dedicated to the citizens who do grassroots environmental work. These include the American activist Angelo Logan, Civic Exchange founder Christine Loh and the late Chinese advocate Xiao Jiangzhou, who fought to protect Tiger Leaping Gorge when the Chinese government was conducting major dam works.

It is from this perspective that Global Cities studies mass protests like Occupy LA in 2011 and Occupy Central in 2014. It largely steers clear of politics behind these movements, but views the demonstrations as a way that the public physically “occupied” spaces in their city. In Hong Kong, for example, highways normally filled with cars were transformed into a tent city, with walkable avenues, outdoor study rooms, herb gardens and even student-run food and garbage collection systems.

Global Cities concludes, rather pragmatically, that much activism “tends to be reactive and temporary. Protests often fail to address the broader context for change.” They may help the public voice dissatisfaction and identify specific changes. But nobody, yet, has been able to make the “structural reform” needed to transform modern cities into something sustainable across the world. “Such a change may seem distance, bit its need is immediate,” they write.

Joyce Lau has been writing professionally since she walked into the Montreal Mirror offices as a 19-year-old college sophomore, and followed the editors around until they finally acquiesced to letting her compile the band listings for a small fee. Her days at McGill University were spent typing away in the basement newsroom of the Tribune, the campus paper. She soon graduated to publishing in magazines like Canadian Business, NOW and Toronto Life. In Hong Kong, she worked as the managing editor of HK Magazine, and as the arts editor of The South China Morning Post, where she still writes freelance book reviews. Most of her journalism career has been at The New York Times, where she specialised in penning long-form features on art and culture. Joyce now works for Civic Exchange, an environmental policy think-tank. She lives in Hong Kong with her husband, two young daughters and an elderly cat.